Figure 3.
Mechanism of swelling in iso-osmotic solutions of NH4 + salts according to classical (A) and novel (B) modes. (A) In the first mode, NH3 diffuses across the membrane, down a concentration gradient (I). Inside the mitochondrion, NH3 associates with a proton to form NH4 +. Pi− is transported in symport with H+ on the Pi carrier (PiC); in the matrix Pi− is in equilibrium with Pi2− that exchanges for dicarboxylate (Dic2−) on the dicarboxylate carrier (DIC) (II), which in turn may exchange for oxodicarboxylate (OxoDic2−) or tricaboxylate (Tric2−) on the dicarboxylate-tricarboxylate carrier (DTC) (III); (B) In the second mode, anion (A−) uptake may be mediated by PIMAC, whereas NH4 + is transported via PmitoKATP. i.m.m., inner mitochondrial membrane; i.s., intermembrane space; o.m.m., outer mitochondrial membrane.